Repeaters, distributed antenna systems, and similar signal repeating systems are wireless communication systems that are used to extend coverage into areas where the radio frequency (RF) signal penetration from base transceiver stations (BTS's) is limited or not present. Those low signal or no signal areas might be inside buildings, in tunnels, shadowed areas that are behind mountains, underground train systems, and various other isolated areas. Generally, applications for such repeater communication systems are for situations where the repeater or distributed antenna system (DAS) is immobile and is mounted in a fixed location with respect to one or more base transceiver stations. In other applications, the area that has limited penetration of the RF signals is mobile. That is, the repeater or distributed antenna system is installed in a moving or mobile conveyance such as a train, ship, car, bus, or airplane.
A mobile communication system, such as a repeater or a DAS typically has various configuration parameters or operational settings that include, for example, filter definitions (Start and Stop frequency or center frequency and bandwidth, filter type), gain settings and/or set power level settings for each filter section, modem or communication settings, and general operational settings (On/Off). These settings must be adjusted at system initialization or set up to allow the repeater to operate properly with the donor BTS, or within the parameters of a certain service provider. The settings typically do not change regularly for fixed repeater systems once they are initially set or programmed.
For mobile repeater applications, such as a repeater system used to extend coverage inside a train car, the areas that the moving system is travelling through might not allow the repeater system to keep the same configuration or configuration parameters for proper operation. As the repeater moves from one cellular service coverage area to another, the established frequency sub-bands and standards available for network communication may change. For example, certain trains may travel between countries, and thus, may be exposed to or use BTS's that are configured for different bands and standards. Various other operational conditions may change as well, such as the downlink signal strength as the mobile repeater system moves with respect to the BTS. It would be desirable for a mobile communication system or other mobile RF transmission system to accommodate these changes as the train travels
To this end, prior systems have attempted to use the global positioning system (GPS) to determine the location of the repeater system. However, GPS receivers are costly and typically require installation of additional antennas on the rooftop of the train or other mobile platform in which the repeater is installed. Installing a GPS external antenna on the rooftop of the train or elsewhere in the mobile platform may be difficult, which may add significant additional expense. Further, depending on the type of train, access to a mounting location for the GPS antenna may not be available. In addition, train tracks often go through tunnels, mountainous terrain, and/or urban canyons were GPS satellite reception itself is inadequate to provide the necessary location information for the repeater system.
Therefore, there is a need for methods and systems for determining the location of repeater systems for use in mobile platforms that do not rely primarily on GPS functionality or require additional external antennas to be mounted with respect to the mobile platform.